This invention relates to a knuckle joint, more particularly to a knuckle joint having two pivotally connected pieces which can be securely engaged with each other.
Referring to FIG. 1, a sectional view of a conventional knuckle joint is shown. The knuckle joint includes a first piece 1 having a flange 11 which is pivoted to a second piece 12 by means of a rivet 110. The second piece 12 has a controlling button 121 for positioning the first piece 1 with respect to the second piece 12. The controlling button 121 has a restraining ring 123 which is retractably received in a arcuated groove 124 formed in the flange 11 of the first piece 1. When the controlling button 121 is depressed to enable the restraining ring 123 to protrude out from the groove 124 of the first piece 1, said first piece can be rotated relative to the second piece 12. However, such a knuckle joint suffers from the following disadvantages:
(1) A clearance is formed between the flange 11 of the first piece 1 and the second piece 12 for the purpose of relative rotation. This results in a loose engagement between the first and second pieces 1, 12 creating structural instability.
(2) The restraining ring 123, which is fitted within the groove 124 of the first piece 1 for checking the relative rotation between the first and second pieces 1, 12, slips within the groove 124 when an excessive torque is exerted on the first piece 1. That is to say, the restraining ring 123 cannot securely position the first piece 1 relative to the second piece 12.